Heat sinks are used in electronic equipment designs to transfer heat from a heat source, such as an electronic component, to lower temperature surroundings. The objective of a heat sink is to lower the temperature of the heat generator to prevent performance degradation and prolong the life of the heat source. A typical heat sink comprises a bottom plate and a plurality of fins. The plurality of fins are vertically attached to the bottom plate and configured to form a series of longitudinal channels. To transfer heat from a heat source, the bottom plate of the heat sink is affixed to the heat source such that thermal contact is achieved with the heat source. Heat is conducted from the heat source to the bottom plate which is then conducted to the fins where it is dissipated by thermal transfer to the lower temperature surroundings, such as air passing through the longitudinal channels. The typical heat transfer rate of a heat sink ranges from 50 to 200 watts per square foot, and is dependent upon extended surface area available, operating ambient temperatures, and material/material thickness.
The effectiveness of a heat sink depends on its ability to transfer heat from the heat source to the lower temperature surroundings. Some factors influencing this ability includes the heat transfer rate of the material from which the heat sink was constructed and the surface area of the heat sink. The heat transferring ability of a heat sink may be increased using a material with a higher heat transfer rate to construct the heat sink. Heat sinks typically comprises one solid piece of material that has a high conductivity with an adequate mechanical strength for secondary support functions. The materials that possess these qualities include metals or metallized plastics, such as aluminum and copper. The heat transfer rates for the aforementioned metals and metallized plastics are as follows: 0.19 deg Celsius/Watt-inch and 0.1 deg Celsius/Watt-inch, respectively. The heat transferring ability of a heat sink may also be increased by increasing the surface area through which heat may be dissipated, e.g., lengthen the fins. This, however, translates into increases the heat sink's size and weight. Such increases are undesirable especially when space is limited.